Of the eight Paths, which are furthest from and which are closest to bringing an end to samsara?
The Righteous Path is furthest from and the Tantra Path is closest. Souls in the Righteous Path have more lifetimes to go before graduating from the School of Life on Earth, while souls in the Tantra Path are preparing for graduation as we speak.
However, Tantra Path is fraught with dangers when engaged by students who are not yet ready, and when facilitated by teachers who are not qualified. This is no indictment, it is simple logic. One should not attempt a 4th-year psychology, chemistry or physics class at university before having completed required preparatory courses—the student just wont get enough of it and the little she gets may even prove to be dangerous when put to use.
Of the eight Paths, how do I know which Path I should choose?
The Path calls you.
You must investigate all the Paths. The right Path for you at the time, is the one that most appeals to you as a truth, a dharmic challenge, not necessarily the one in which you feel most comfortable.
There may be higher aspects of your current path that you have not yet achieved or considered. It is not always necessary to change paths. If you feel that you still have a way to go in your current Path, and you find it challenging, you are on the right Path for now.